* invalid URL. You can even be explicit about whether each component has been encoded already.
 *
 * [idna]: http://www.unicode.org/reports/tr46/#ToASCII
 */
class HttpUrl private constructor(
  /** Either "http" or "https". */
  @get:JvmName("scheme") val scheme: String,
  /**
   * The decoded username, or an empty string if none is present.
   *